Cover Window Coating Structure for Scratch Resistance Without Bending
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Solution Overview
Problem
Display devices using plastic cover windows are prone to bending and scratching due to hard coating layers contracting during curing, which affects their performance and durability.
Innovation Solution
A cover window structure with alternating layers of acryl-based and silicon-based or epoxy-based organic-inorganic materials, where each layer curls in opposite directions during curing, canceling out bending forces and preventing deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard coating layer is formed on a plastic cover window, then the scratch resistance is improved, but the cover window bends due to coating layer contraction during curing
Solution Approach 1:
The hard coating layer is divided into multiple sub-layers (first hard coating layer, second hard coating layer, and third hard coating layer) with different materials. This segmentation allows each layer to have different contraction characteristics, and the combined structure balances the overall contraction force, preventing bending while maintaining scratch resistance.
Solution Approach 2:
The invention changes the material composition parameters of the hard coating layer by using different organic-inorganic materials (acryl-based, silicon-based, epoxy-based) with varying crosslinking densities and contraction rates. By adjusting these material parameters across multiple layers, the overall contraction behavior is controlled to prevent bending.
2Strength
If glass is used as cover window material, then the hardness and scratch resistance are improved, but the impact resistance deteriorates making it easily broken
Solution Approach 1:
The invention uses composite organic-inorganic materials that combine the hardness benefits of inorganic components (silica, epoxy) with the flexibility and impact resistance of organic components (acryl-based polymers). This composite structure achieves both high hardness for scratch resistance and sufficient flexibility for impact resistance, eliminating the need for pure glass.
3Reliability
If plastic material is used for cover window, then the impact resistance is improved, but the scratch resistance deteriorates making the surface easily scratched
Solution Approach 1:
The plastic base layer is combined with organic-inorganic hard coating layers that provide enhanced scratch resistance. The composite structure maintains the impact resistance of the plastic substrate while the hard coating layers provide the necessary surface hardness to resist scratching from pointed objects.
Solution Approach 2:
The multi-layer curved structure of the coating system (with each layer having optimized thickness and material composition) creates a gradient transition from the plastic substrate to the hard surface, allowing stress distribution that maintains impact resistance while providing scratch resistance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The multi-layered coating structure enhances the cover window's resistance to bending and scratching, maintaining structural integrity and performance while providing sufficient hardness.
Implementation Method 1
a cover window which is prevented from bending as a hard coating layer is contracted during a curing process
Data Source
AI summary
A cover window includes a base layer. A first hard coating layer is disposed on a first side of the base layer. A second hard coating layer is disposed on the first hard coating layer. The first hard coating layer comprises an acryl-based organic-inorganic material and the second hard coating layer comprises a silicon-based or epoxy-based organic-inorganic material; or the first hard coating layer comprises the silicon-based or the epoxy-based organic-inorganic material and the second hard coating layer comprises the acryl-based organic-inorganic material.